000
AXNT20 KNHC 171741
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN MAR 17 2013

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL 
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF 
SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE 
EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE 
IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL 
ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1715 UTC.

...ITCZ/MONSOON TROUGH... 

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 10N14W TO 
07N16W TO 06N19W. THE INTERTROPICAL CONVERGENCE ZONE AXIS 
EXTENDS FROM 06N19W TO 04N24W TO 01N28W TO THE EQUATOR NEAR 31W 
AND ALONG THE EQUATOR TO 42W. SCATTERED MODERATE CONVECTION IS S 
OF 04N BETWEEN 21W-32W.

...DISCUSSION...

GULF OF MEXICO...                                           
MOIST SOUTHWESTERLY UPPER LEVEL FLOW IS EVIDENT ON WATER VAPOR 
IMAGERY WITH MID-LEVEL SHORTWAVE ENERGY PROGRESSING 
NORTHEASTWARD ACROSS THE NORTHERN GULF CENTERED NEAR 28N92W. 
THIS FEATURE ALOFT IS PROVIDING FOR INCREASED CLOUDINESS ACROSS 
THE BASIN GENERALLY N OF 24N W OF 93W. MOSAIC DOPPLER RADAR AND 
LIGHTNING DATA ALSO INDICATE WIDELY SCATTERED SHOWERS AND 
ISOLATED ELEVATED TSTMS ARE OCCURRING OVER THIS AREA INCLUDING 
INLAND COASTAL LOCATIONS S OF 31N BETWEEN 84W-90W. OTHERWISE... 
SOUTHERLY RETURN FLOW DOMINATES ACROSS THE GULF THIS AFTERNOON 
ON THE WESTERN PERIPHERY OF A BROAD EAST-WEST ORIENTED RIDGE 
ANCHORED IN THE SW NORTH ATLC. THE SHORTWAVE TROUGH IS FORECAST 
TO CONTINUE ITS NE MOVEMENT OVER THE NEXT 12 TO 24 HOURS WITH 
SOUTHERLY SURFACE WINDS PERSISTING THROUGH LATE MONDAY AS THE 
RIDGING GRADUALLY SLIDES EASTWARD. BY EARLY TUESDAY A WEAK FRONT 
IS EXPECTED TO EMERGE OFF THE TEXAS AND LOUISIANA COAST.

CARIBBEAN SEA...                                            
UPPER LEVEL SOUTHWESTERLY FLOW IS NOTED ON WATER VAPOR IMAGERY 
DUE TO A BROAD ANTICYCLONIC CIRCULATION CENTERED WELL SE OF THE 
BASIN NEAR 06N55W. WHILE MOST OF THE SOUTHWESTERLY FLOW IS DRY 
AND FAIRLY STABLE...A FEW AREAS OF LOW-LEVEL MOISTURE AND 
PRECIPITATION ARE OCCURRING ACROSS THE BASIN. A SHEAR LINE IS 
ANALYZED ACROSS THE CENTRAL ATLC TO A TERMINUS NE OF THE LEEWARD 
ISLANDS NEAR 18N61W. RESIDUAL MOISTURE AND ISOLATED SHOWERS 
CONTINUE TO DRIFT SW OVER THE NE CARIBBEAN REMAINING N OF 16N E 
OF 68W. ANOTHER AREA OF ISOLATED SHOWERS ACCORDING TO SATELLITE 
IMAGERY IS FOUND S OF 14N BETWEEN 63W-74W. MOST OF THE REMAINDER 
OF THE CARIBBEAN IS UNDER THE INFLUENCE OF TRADE WINDS IN THE 
RANGE OF 15 TO 25 KT WITH THE STRONGEST AREA LOCATED GENERALLY S 
OF 17N BETWEEN 69W-79W...AND IN CLOSE VICINITY TO THE COAST OF 
COLOMBIA. THIS SYNOPTIC PATTERN IS EXPECTED TO PERSIST THROUGH 
MID-WEEK.  
 
ATLANTIC OCEAN...                                       
GENERALLY WESTERLY MIDDLE TO UPPER LEVEL FLOW IS DOMINATE OVER 
MUCH OF THE ATLC BASIN W OF 40W WITH A FAIRLY BROAD SURFACE 
RIDGE COMPLETING THE VERTICAL PROFILE OF OVERALL STABLE 
CONDITIONS THIS AFTERNOON. THE SURFACE RIDGING IS ANCHORED BY A 
1025 MB HIGH CENTERED NEAR 27N62W. TO THE EAST...A MID-LEVEL 
SHORTWAVE TROUGH IS NOTED ON WATER VAPOR IMAGERY CENTERED IN THE 
VICINITY OF 35N33W THAT SUPPORTS A COLD FRONT ANALYZED INTO THE 
DISCUSSION AREA NEAR 32N34W. THE FRONT EXTENDS SW TO 25N40W TO 
23N46W AND THEN BECOMES A SHEAR LINE TO 22N50W TO 18N61W. 
ISOLATED SHOWERS ARE OCCURRING WITHIN 90 NM EITHER SIDE OF THE 
FRONT AND WITHIN 120 NM EITHER SIDE OF THE SHEAR LINE AXIS. THE 
BROAD RIDGING IS FORECAST TO EXPAND ITS INFLUENCE NEARLY THE 
ENTIRE DISTANCE ACROSS THE ATLC WITH AXIS ALONG 27N/28N BY LATE 
MONDAY. THE NEXT COLD FRONT TO EMERGE OFF THE SE U.S. COAST IS 
EXPECTED EARLY TUESDAY.

FOR ADDITIONAL INFORMATION PLEASE VISIT 
HTTP://WWW.HURRICANES.GOV/MARINE

$$
HUFFMAN